1. Field of the Invention
The present invention relates to a polypeptide composition and a culture method for pluripotent stem cells using the polypeptide composition.
2. Description of the Related Art
For the purpose of the recovery of functions of damaged tissues, various regenerative medical techniques are being developed. Among these, a large number of techniques relating to totipotent or pluripotent stem cells of primates, particularly, human beings that is ultimately aimed at the regeneration of tissues has been reported. Especially, induced pluripotent stem cells (iPS cells) have an advantage in that these cells lessen ethical issues because they are induced from somatic cells unlike embryonic stem cells.
In a case where the totipotent or pluripotent stem cells (both will be collectively simply referred to as “pluripotent stem cells” in the present invention) of primates are cultured, the pluripotent stem cells need to be kept undifferentiated over a long period of time. For culturing the undifferentiated pluripotent stem cells over a long period of time, generally, feeder cells such as mouse fibroblasts are used.
However, it has been pointed out that the use of heterogeneous animal-derived feeder cells such as mouse fibroblasts leads to a likelihood that foreign substances such as heterogeneous animal-derived antigenic substances may be mixed into the culture solution. Therefore, in a case where the totipotent or pluripotent stem cells are used for medical purposes or for the purposes equivalent to medical purposes, the cells need to be cultured in the absence of feeder cells.
In consideration of the circumstances described above, cell-adhesive materials functioning as the feeder cells are being developed. For example, Nature Biotechnology, 2001, Vol. 19, pp. 971-974 discloses that human embryonic stem cells kept undifferentiated are successfully cultured by using matrix gel which is a component extracted from mouse sarcoma as a substituent for feeder cells.
JP2001-17183A discloses a feeder cell-free cellular composition containing growing primordial cells of primates, and discloses, as a preferred embodiment, a cellular composition further containing an extracelluar matrix. JP2010-29186A discloses a cell culture substrate in which a plasma-polymerized cell culture surface is coated with a coating solution containing an extracellular matrix protein at a predetermined concentration and an aqueous solvent. JP2010-29186A describes that the cell culture substrate has excellent adhesiveness helpful to avoid the differentiation of embryonic stem cells.
Biomaterials, 2010, November; Vol. 31(32), pp. 8281-8288 and Nature biotechnology, 2010, Vol. 28, No. 6, pp. 606-610 disclose a recombinant peptide or a synthetic peptide including a partial sequence of vitronectin that makes a contribution to long-term culture of embryonic stem cells. Specifically, the above documents disclose a polypeptide as an amino acid sequence consisting of the 1st to 52nd amino acids in the amino acid sequence of natural vitronectin (see Biomaterials, 2010, November; Vol. 31(32), pp. 8281-8288) and a polypeptide as an amion acid sequence consisting of the 40st to 52nd amino acids of natural vitronectin including an RGD sequence (see Nature biotechnology, 2010, Vol. 28, No. 6, pp. 606-610) respectively. It is known that these polypeptides make it possible to avoid a likelihood of intermixing of antigenic substances because they are non-biological samples and can be excellently produced in an industrial manner.